Art of pyrogenetic conversion of hydrocarbon oils



11. 2 1927. F. A. HOWARD ET AL ART OF PYROGENETIG CONVERSION OFHYDROCAiBON OILS Filed May 23, 1921 4 Sheets-Sheet 1 WW) i r 1HJHHUHHWHH wfl a I i, QN m m m rkfl .Q E L km 2% I. n

4 Sheets-Sheet 2 lfl llllildllll R 1 firl 1 11 L rll l1 Jan. 25 1927.

F. A. HOWARD ET AL ART OF PYROGENETIC CONVERSION OF HYDROCARBON OILSFiled May 25, 1921 1 615 384 1927' F. A. HOWARD ET AL ART OF PYROGENETICCONVERSION OF HYDROCARBON OILS Filed May 23, 1921 4 Sheets-Sheet 5 Jan.25, 1927.

F. A. HOWARD ET AL ART OF PYROGENETIC CONVERSION OF HYDROCARBON OILSFiled May 23, 1921 4 Sheets-Sheet 4 .fizverzZom,

Patented Jan. 25, 1927.

UNITED STATES PATENT OFF 1,615,384 IC E.

FRANK A. HOWARD, OF ELIZABETH, NEW JERSEY; EDGAR M. CLARK, OF NEW YORK,N. Y.; AND JAMES R. CARRINGER, F ELIZABETH, NEW JERSEY, ASSIGNORS TOSTANDARD DEVELOPMENT COMPANY, A CORPORATION OF DELAWARE.

ART OF PYROGENETIG CONVERSION OF HYDROCARBON OILS.

Application filed May 23, 1921, Serial No. 471,724, and in theNetherlands January 15, 1921.

The present invention relates to the pyrogenetic conversion of heavierhydrocarbon oils under pressure into lighter hydrocarbon oils, forexample, of the character of gasoline, and will be fully understood fromthe following description thereof, illustrated by the accompanyingdrawings, in which Figure 1 is a view in side elevation of a still andsetting suitable for carrying-out the invention, these being shownpartly broken away and partly in section;

Figure 2 is an end elevation of the still and setting, viewed fromthe'right-hand end of Figure 1;

Figure 3 is a transverse vertical section' through the still;

Figure 4' is a longitudinal vertical sectional View through the still online 4-4 of Figure 3; and

Figure 5 is a plan view of the still and setting partially brokenawayand shown in part in horizontal section.

Referring more particularly to the .drawings, the numerals 10, indicatespaced setting walls of suitable masonry construction within which thestill and the heating chamber are enclosed. At each end ,of the settingthere are formed fire-places l1 and 12, which communicate with a heatingchamber 13 of suitable refractory construction, and which extends withinthe setting walls 10, 10 for the greater part of their length. Thisheating chamber is of approximately rectangular cross-section. Thefire-places 11 and 12 may be provided with any suitable firing means,for example, the oil burners 14 and 15, respectively, and the combustiongases therefrom pass through the heating chambers. A shallowchecker-work 16, 16 is arranged in the bottom of each of thetire-places, and openings 17 from the exterior to this chcckerork areprovided for the admission of air. At each end of the setting, atapproximately the point where the fire-places open into the heatingchamber 13, flues 18 and 19 open, each of them leading to a main flue 20leading to a stack (not shown). The dampers 21 and 22 are provided toclose the fines 18 and 19. respectively, when desired.

Below the heating chamber 13, and outside of its walls, the twolongitudinally extending drums 23 and 24 are provided. which areof'similar construction. Each of them of equal length are provided, oneon each side of the median line through the heating chamber. These drumsare of similar construction, each being provided with transversepartitions 28 which completely close the drum, thereby dividing themeach into a plurality of short compartments. The drums 26 and 27 arewith the drums 23 and'24, and the. intervals between the partitions ineach of the drums are substantially equal. Above the drums 26 and 27,preferably between them, a longitudinal cylindrical drum 29, ofsubstantially the same length as the previously mentioned drums, issuitably supported, for example, on the transverse beams 30 which aresupported on the vertical beams 31. This uppermost drum 29 is providedwith transverse partitions 32, 32, which ere tend from the bottom ofthedrum to a point spaced from the top, whereby free com municationalong the top of the drum is permitted. The partitions 32. 32 in thedrum 29 are spaced apart a distance equai to the spaces between thepartitions in the previously mentioned drums.

Referring more particularly to the group of drums comprising drums, 23,2 1, 26 and 27, communicating heating tubes 33, 33 are provided whichextend diagonally upwards through the heating chamber between the drumsabove and below the said chamber on ,opposite sides of the median linethere through, that is, the tubes communicate from drum 23 to drum 27and from 24 to drum 26. A set of such tubes is provided for eachcomparement between the partitions in the several drums. In addition foreach such compartment, a large tube or pipe 34., which may be designatedas a downcomer, ere tends from each of the upper drums to the lower drumon the same side of the. median line through the heating chamber, thatis, from drum 26 to drum 23 and from drum 27 to drum 24. These(lowncomcrs 34, 34-. pass outside of the heating chamber 13, but.

inside of the settin wall 10. The two bottom drums 23 an 24 communicatewith each other by the pipes '34 of which a considerable number, forexample, two, are provided for each of the intervals between theartitions in said drums. From each of the drums 26 and 27 largecommunicating pipes extend to the top drum 29, there being at least onesuch communicating pipe for each compartment between partitions in thesaid drums. The drum 26 is provided near each end with a valved ipe 36,which may be designated as an over ow pipe. Pipes 37, provided withsuitable valves.;37", enter the top drum 29 near each end, and may bedesignated as the feed pipes. Each of the lower drums 23 and 24- isprovided with a draw-ofl pipe 38, 38, these connecting with a centralbottom discharge crime 39. A vapor-line 40 communicates with the vaporspace in the top drum- 29 and leads to a suitable runback ordephlegmator and condensing devices (not shown). It will be apparentthat the partitions within the drums divide the still as a whole intosections in which the oil is confined, each of these sections having itscorresponding heating tubes and downcomers, the vapor spaces of thesesections communicating at the top and the oil-containing spacescommunicating at the bottom.

In the operation of pressure cracking stills, wherein a heavyhydrocarbon oil is heated under sufficient pressure to maintain it inthe liquid phase, to convert it into lower boiling oint hydrocarbons,such as gasoline, it is esired to prevent the exces sive formation ofaromatic products to such an extent as to give dominantly aromaticcharacteristics to the cracked dist-illate or naphtha produced. Incontinuous tube cracking rocesses as hitherto practiced. and asistinguished from pressure-still cracking processes in which the vaporsof the lighter converted hydrocarbons are withdrawn from the oilsubstantially as soon as formed, it has hitherto been the experience inthe art that a product having dominant aromaticcharacteristics has beenproduced. These characteristics evidence themselves not only in thehighly aromatic odor and yellow color of the distillate, but also in itspghysical characteristics, and particularly its aum gravit whenconsidered with reference to the boilin point of the distillate and ofits various i ractions. For example, in comparing a tube-cracked naphthawith a. pressure-still naphtha having a similar range of boiling points,the following is found: The tube-cracked naphtha had a.

Baum gravity of 49.9, the pressure still naphtha 58.9.: The odor of thetubecracked naphtha was highly aromatic, that of the pressure-stillnaphtha was gasolineiike. The acid heat developed by the tubecrackednaphtha was 61' F, 19- per cent being absorbed by 66 Baum acid. The acidheat developed by the pressure-still 'naphtha was 24 F., 11 per centbeing absorbed by 66 Baum acid. It is thus apparent that thetube-cracked naphtha, in addition to its aromatic odor, indicates itsdominant aromatic characteristics by its greater density and the greateracid heatdeveloped. Tn the following specification and claims productsof these types will be indicated as having dominant aromaticcharacteristics and as having dominant paraflinoid characteristics,respectively.

In accordance with the present invention, a heavy hydrocarbon oil isheated under pressure while flowing in a continuous stream through aheated zone, and under such conditions as to secure a crackeddistillation product containing lower boiling pbint oils havin adominant paraiiinoid character, as distinguished from the products ofprior tube-cracking processes in which a distillate of dominant aromaticcharacter was produced. In order that this process may be more clearlyunderstood, it is hereinafter described as carried out in the apparatuswhich has been hereinbefore described in detail. The stock to beconverted may be. for example, a heavy distillate of the character ofgas-oil having a gravity of 32 to 34 B6. The stock is sup plied to thestill through the feed-pipe 37 near one end of the drum 29, for example,near that end at which the fire-place 11 is located. The stock fills thedrums and the communicating tubes flowing in the direction of the otherend of the still. The still may be heated by means of either of thelireplaces 11 or 12, it being preferred that the i fireplace 11 beemployed, so the combustion gases travel through the heating chamber 13in the direction of flow of the oil through the device. The fine 18 isthen closed and flue 19 opened. The-oil is divided by the partitions inthe drums into units, each of which gives oil its vapors into the commonvapor space in the top drum and communicates with the remaining units inthe lower drums. The heat is so conducted as to bring the oil as rapidlyas possible to a high cracking temperature at which the rate of thisconversion into lighter hydrocarbons of the character desired shall notbe less than 36 per cent per hour, that is, not less than 810 to 820 F.A temperature of 800 to 1000 F. is preferred. By causing the combustiongases to pass through the heating chamber in the direction of flow ofthe oil, this temperature is rapidly acquired by the oil undergoingtreatment, and the residual heat of the combustion gases as they passthrough the heating chamber maintains the oil at the desiredtemperature. As a result of the heatgm. an

the point of feed.

ing of the oil in the tubes within the heat ing chamber, a rapidthermocyclic circulation through the tubes is produced. The oil enteringinto the first compartment between the head of the drum 29 andt'he firstpartition descends through the. corresponding pipes into thecorresponding compartments. in. the drums 26 and 27 and'throu h thetubes 33 and downcomers 34 into tie corresponding compartment in 'drums23 and 24; The space left in the bottom of the drums for freecommunication the entire length of the drums permits the oil to travelthe length of these lower drums and fill up the entire oil space in thestill. When the' thermocyclic circulation has been established, the oilin the lower drum in the interval between any two partitions thereinflows rapidly upward through the tubes 33 to the corresponding intervalsor compartments in the drums 26, 27 and 29, a downward flow beingestablished through the j downcomers 34.- There is thus a rapidcirculation in each unit of oil through the heated zone and of'oil fromeach unit to the succeeding one. The vapors of lighter hydrocarbonsproduced during the passage of the oil through the heated zone aresubstantially immediately evolved, passing out through the vapor-spacein the to drum 29 and the vapor-line 40 to the con enser system. systemsuflicient to maintain the c arging stock in the liquid phase at thetemperature of treatment, this pressure being at least 150 poundsIpressur'e, although greater pressure maybe employed to increase theconcentration of the lighter hydrocarbons in the liquid phase of the oilundergoing treatment and in the vapors issuing therefrom.v

The oil circulating through the tubes gradually travels towards theopposite end of the drums from which it feeds, the bottoms beingcontinuously removed from the bottom drum through the tar-lines 38 and39. As the lighter hydrocarbons re produced and evolved, the "volume oftie Oil in the successive units decreases, with the result that :thelevel of the oil in the top drum 29 gradually drops from compartment tocompartment the greater'the distance from The distillate produced fromthe va )ors of the still operated in the manner a ove described hasdominant ,parafiinoid characteristics, notwithstanding the high crackingtemperature to which the?- charging stock is subjected 'for the periodof its travel through the still. It is believed that this .is due to theremoval of the lighter hydr carbons from the cracking zone substantial-"1y;- immediately upon formation, whereby no'further cracking orbreaking down of the lighter hydrocarbons into aromatic compounds isproduced and the 011 passing A pressure is maintained u on the throughthe zone is substantially entirely in the liquid phase. The retention.of the lighter hydrocarbons in the cracking zone,

particularly at the high temperatures to which they are subjected, wouldresult in the formation of large proportions of aro- 'matics as is theexperience in tube cracking processes, the resulting distillate thenbeing of a dominantly aromatic character as is the case with thedistillates produced art.

It is not -intended that the temperatures employed shall be limited totemperatures approximating the minimum temperature hereinbefore stated.Higher temperatures, for example, temperatures of the order of 1000 F.may be employed while utilizing pressures of say 250 to 300 ounds orabove, suflicient .to maintain the cliargin stock in the liquid phase.In such case, t 1e rate of cracking into lighter hydrocarbons-ofdominantly paraflinoid characteristics becomes very greatly increased,their immediate re"- moval from the cracking zone, however,

result in the formation of a distillate havingdominantly aromaticcharacteristics.

In continual operation of thestill it is desirable to alternate thedirection of feed and'direction of movement of combustion gases attimes, thereby equalizing the wear on the cracking tubes.

Although the present invention has been described in connection withspecific details of anapparatus suitable for carrying it into in thetube-cracking processes known in the preventing excessive cracking whichwould effect, and of a process for its emplo ment,- I

it is not intended that these details s all be regarded aslimit-ationsupon the sec e of the invention, except in so far as inc uded in theaccompanying claims.

We claim:

' 1. The process of pyrogenetic conversion of hydrocarbon'oils intolower-boiling point oils having dominant parafiinoid character isticswhich consists in continuously flowing the hydrocarbon oil through azone heated to a temperature suflicient to cause conversion of the oilata rate of at least 35% per hour and under a pressure sufiicient to'maintain the said oil in the liquid phase tinuously ficient to maintainit in the liquid phase and continually removing the vapors of lighthydrocarbons from each of said units substantially immediately uponformation during passage through the heating zone.

3. The process of pyrogenetic conversion of hydrocarbon oils into lowerboiling point oils having dominant parafiinoid characteristics whichconsists in maintaining the oil in a plurality of communicating units,causing the oil of each unit to flow upwardly through a heated zonewhereby it acquires a temperature suflicient to cause conversion at arate ofat least 35% per hour, and continuously withdrawing vapors oflight hydrocarbons from .each of said units while passingthrou h theheating zone, a pressure being maintained upon the oil at leastsuflicient to retain it in the liquid phase.

4. The process of pyrogenetlc conversion of hydrocarbon oils into lowerboiling point oils having dominant paraflinoid characteristics whichconsists in maintaining a plurality of communicating units of oil,conflowing the oil into and progressively tirough said units, causingthe oil of each unit to flow through a heated zone whereby it acquires atemperature sufiicient to cause conversion at a rate of atleast 35% perhour, and continuously withdrawin v'a pors of light hydrocarbons fromeac of said units, a pressure being maintained on the oil at leastsufiicient to retain it in the liquid phase.

5. In a pressure oil still, an upper and a lower. drum, each beingpartitioned into compartments, a heating vzone between the drums,communicating means between the corrcsonding compartments of the drumsexten ing through the heating zone, communicating means between thecorresponding compartments of the drums outside of theheating zone,means for collecting the vapors from the several compartments of theupper drum, and means establishing communication between thecompartments in the lower drum.

6.- In a pressure oil still, a pair of upper drums, and a air of lowerdrums, each of said drums ing partitioned into comartments and thecompartments of the ower drums communicating at their hottoms, a heatingzone between the pairs of drums, the drums of each pair being onopposite sides of the median line through the heating zone,- heatingtubes extending between the compartments of each of the lower drumsthrough the heating zone to the corresponding compartments of the upperdrum on the opposite side of the median line through the heating zone,communicating means between the compartments of each of the upper drumsand the corresponding compartments of the lower drum on the same side ofthe medianline through the heating zone, said communicating meanspassing outside of the heating zone, means for collecting vapors fromthe upper drums, means for feeding oil into the compartments of theupper drums and means for withdrawing oil fromthe lower drums.

7. In a pressure oil still, a pair of upper drums, and a pair of lowerdrums, each of said drums being partitioned into compartments and thecompartments of the lower drum's communicating at their bottoms, aheating zone between the pairs of drums, the 'drums of each pair beingon opposite sides of the median line through the heating zone, heatingtubes extending between the compartments of each of the" lower drumsthrough the heating zone to the corresponding compartments of the upper.drum on the opposite side of the median line through the heating zone,communicating means between the compartments of each of the upper drumsand the corresponding compartments of the lower drum on the same side ofthe median line through the heating zone, said communicating meanspassing outside of the heating zone, a drum above the upper drums, saiddrum being divided into compartments communicating at the to of thedrum, communicating tubes exten ing from the compartmentsof thelast-mentioned drum to the corresponding compartments of the upper pairof drums, means for withdrawing vapors from the drum above the upperdrums and means for withdrawing oil from the lower drums.

FRANK A. HOWARD. EDGAR M. CLARK. JAMES R. oARRrNenn

